#95 Comparator vs Comparable in Java

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In this lecture we will learn:
What is Comparator in Java?
How to give your implementation for sorting?
What is Comparable in Java?
Difference between Comparable & Comparator
#1
From the Java 1.7 version, it is not compulsory to mention the generic type on the right-hand side if you have already mentioned it on the left-hand side.
A collection class has lots of methods. The collection class belongs to the util package.
We can sort a list or an ArrayList by using the method sort of collection class
Collections.sort();
If we want to apply our own logic in sorting, then we have to use a comparator with sorting in collections.
Comparator is also an interface.
We have a method called compare() in the comparator interface.
We can use an interface by implementing a class or through an anonymous class.
Compare method works on an algorithm where it compares two values and then swaps them.
Comparator Integer com= new Comparator Integer()
{
public int compare(Integer i, Integer j)
{
statements;
}
};
So, a comparator is an interface through which you can specify your own concept of sorting.
#2
Integer class implements a Comparable interface. So by default, sort works for Integer.
If you want to do natural sorting on any other non-defined class, you can implement something called the Comparable.
Comparable is present in the lang package.
Comparable has a method known as compareTo().
You have to define the method comapreTo() in a class, that is implementing Comparable.
class Student implements Comparable Student
{
public int compareTo( Student that){
statements;
}
}
Here, that is a variable.
We can also override the logic by using Comparator even if we have implements the Comparable interface.
Lambda expression can also be used with Comparator as it is a functional interface.
#3
Difference between Comparable & Comparator:
Comparable provides a single sorting sequence while the Comparator provides multiple sorting sequences.
In Comparable, actual gets modified while in Comparator, the original class does not get affected.
Comparable gives the compareTo() method for sorting while Comparator gives the compare() method to sort elements.
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[@naul2k74]

You literally teach and explain everything about sorting with object in 15 mins that my professor wasn't able to do in 2 hours. Good job and keep doing these things because it's really helpful and valuable to a fresher like me

[@jnslzr]

same, our teacher here literally sent us to read javadocs =)

[@Noah-zc6mv]

So glad you're updating your older videos. Helpful as always! 😁

[@suhailsharieff155]

Navin sir.... Really fond of u..... I sat for 5 hrs to understand it.... Now im crystal clear

[@sciencequotesfacts5543]

can you give some techniques

[@rhea1149]

best java instructor i’ve ever come across

[@varsheethtv2459]

The last 2 mins are very insightful!! 😍😍

[@Democracy_Manifest]

Good video. Thanks for leaving in the errors so we can learn.

[@shraddhashetty8659]

Sorting the String based on the length: public class PractComparator { public static void main(String[] arg) { Comparator com = new Comparator() { @Override public int compare(String o1, String o2) { return o1.length() - o2.length(); } }; List fruit = new ArrayList(); fruit.add("Banana"); fruit.add("Mandarin"); fruit.add("PineApple"); fruit.add("Apple"); Collections.sort(fruit,com); System.out.println(fruit); } }

[@dypsking3414]

Thank you Mr. You made it very simple and easy!

[@AmeyChittar]

Hi Navin. as usual great video.. but most importantly comparator and comparable have always been things ive never understood.... until now.. the way you have explained is amazing and always wait for your amazing videos. and by the way the growth of your presentation and teaching skills have become better and better and we love it. Thanks a lot and will be waiting for lots more videos.

[@tarekabushaheen7593]

10/10 video and demonstration, absolutely love the dynamic, following along and coding beside you helps to learn efficiently

[@vikrantsingh2804]

I must say this was one of the best videos explaining comparator and comparable concept.

[@moviecraze6079]

Heck of a video! I have been trying to understand the differences for a long time, finally you cleared all of my doubts.

[@ekanshmishra4517]

I have been struggling to understand this for long and this video is what it was required to get it cleared. Thank you @NavinSir #Telusko

[@pratikkumarsingh8114]

Great, got my concepts cleared . Thank you , sir!!!👍👍👍👍👍👍👍👍👍👍👍👍👍👍

[@gurrammahenderreddy4586]

TASK : import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; class Hello { public static void main(String a[]) { Comparator com = new Comparator() { public int compare(String i, String j) { if(i.length() < j.length()) return 1; else return -1; } }; List names = new ArrayList(); names.add("Navin"); names.add("Navin Reddy"); names.add("Telusko"); names.add("Navin Telusko"); Collections.sort(names, com); System.out.println(names); } }

[@statuslover1510]

Correct 👍

[@priyanshukhullar-tc7ss]

Awesome guruji shukriya

[@Sumanth_Siddareddy]

thanks for your explanation, sir. It helps me to understand comparable and comparator.

[@karanraut4417]

@telusko I loved your teaching style Naveen Reddy Sir, It is not necessary for a Comparator to return -1 or 1 it can actually return any negative or positive integer only the sign matters. even 0 is allowed i guess. this caused me confusion but you should have also mentioned it at the end for more nerdy people. package java4AdvancedCollections; import java.util.TreeSet; public class TreeSetExample { public static void main(String[] args) { // Creating a TreeSet of integers (natural ordering) TreeSet treeSet = new TreeSet(); // Adding elements to the TreeSet treeSet.add(10); treeSet.add(5); treeSet.add(20); treeSet.add(15); // Printing the TreeSet (elements will be in ascending order) System.out.println("TreeSet: " + treeSet); // Creating a TreeSet with a custom comparator for descending order TreeSet descendingTreeSet = new TreeSet((a, b) -> { if (a > b) { return -2; } else { return 2; } }); // Adding elements to the descending TreeSet descendingTreeSet.add(10); descendingTreeSet.add(5); descendingTreeSet.add(20); descendingTreeSet.add(15); // Printing the descending TreeSet (elements will be in descending order) System.out.println("Descending TreeSet: " + descendingTreeSet); // Performing operations specific to NavigableSet interface System.out.println("Ceiling of 12: " + treeSet.ceiling(12)); System.out.println("Floor of 12: " + treeSet.floor(12)); } }

[@adityarao7249]

Love your videos, learn new thing every time.

[@beinghuman63393]

Excellent ❤❤ , feeling enjoyed the functional usage at the end

[@inspiredomkar1239]

Logic to sort elements based on the length of the string import java.util.Comparator; import java.util.*; class Solution { public static void main(String[] args) { Comparator com = new Comparator(){ public int compare(String a , String b){ if(a.length() > b.length()) return 1; else return -1; } }; List nums = new ArrayList(); nums.add("Python"); nums.add("C++"); nums.add("Java"); nums.add("Django"); nums.add("SpringBoot"); nums.add("Spring"); Collections.sort(nums , com); System.out.println(nums); } }

[@yusrax3]

finally understood thanks!

[@franciscomambo4120]

Just discovered this video and the explanation is awesome, it almost blew my mind

[@emmaruhcheva3658]

amazing video, gave me the summary i needed!

[@deepthimalepatiii247]

Reddy ji! No words Thanks for your explanation

[@ManojPatil-z8m]

Hats off to you, sir! 🙌

[@mikedelta658]

Now, I understood those concepts. Thanks

[@uLise4Life]

Had to watch an entire tutorial just because I thought I don't undertand java. After this video. i'm like OH MY GOD !!!!!!!!!

[@abrorallaberganov6293]

Great Explanation. Thanks

[@abhinavmishra9690]

Understood today the real concept behind comparator and comparable

[@harshsuchak8370]

Awesome Explanation!

[@lxy2670]

i love you man. I finally got it!

[@student_03]

thats a great video covered all that i needed thank you

[@lovemishra8137]

Nice explaination

[@soumyadeepchatterjee2189]

Very helpful, thank you.

[@rahuljmd]

Homework: import java.util.*; class Solution { public static void main(String[] args) { // Write your code here Comparator com=new Comparator(){ //jai mata di : Anonymous Inner class public int compare(String s1, String s2){ if(s1.length()>s2.length()){ return 1; } else return -1; } }; List al=new ArrayList(); al.add("Rahul"); al.add("DK"); al.add("J"); Collections.sort(al,com); System.out.println(al); } }

[@tej3679]

Thanks for the awesome explanation sir🎉

[@macedoedit5797]

Great video, thanks !

[@Sriram-ii8oo]

Thank you so much for this video ❤

[@vinethasuresh3488]

wonderful video, it helps me to understand the concept very clear . Example you are providing is just awesome sir. keep doing these kind of videos sir. thanks a lot.

[@leonsvideos]

Great explanation, thank you so much!

[@akshaysilgari2097]

Great explanation

[@gyanendramaurya1796]

When i was a student in 2015 then also i used to come and watch java videos here. I now have almost 5 years of experience and when some Java work comes I come here again to refresh my memory. Thank you Navin. It feels like nostalgia sometimes watching your videos

[@nischalofchrist]

This is great explanation.

[@jeffro8807]

your videos are awesome man

[@SphereofTime]

comparable and so no?1:00

[@sai-dx1vb]

How you intantiated the comparator because comparator is an interface and we cannot instantiate interface?

[@zeldaking2429]

Thank you. very clear and helpful!

[@swacharahman5084]

This video is tooo goood. THANK you

[@awkward_adi]

Thank you so much for this.

[@aashuk]

Nice explanation. which IDE is that ? - got it. Visual Studio

[@francksgenlecroyant]

Navin Reddy never disappoints

[@rahuljmd]

Synopsis: If you want to give class the power to compare its object on its own then use Comparable otherwise use Comparator to define logic and pass its object in the Collections.sort() method....

[@kidoo1567]

Thanx jhonny

[@shankil2975]

Excellent video. Well explained. Can you add a comment here on how to sort based on more than one field? Say name and age assuming student names are duplicated. thanks

[@ketansharma6955]

great video sir

[@hmmgmm2841]

something meaningful to me

[@devabdul]

Thank you for valuable video ❤️

[@karanraut4417]

@telusko it is not necessary for a Comparator to return -1 or 1 it can actually return any negative or positive integer only the sign matters. {even 0 is allowed i guess}

[@shriharis.s3296]

Here i have a doubt. Comparable is a functional interface. So we can override onlt compareTo() method and it is fine. But Comparator method is not a functional interface. How can we just override only menthod which is compare() and Java dosen't gives an error?

[@hadse1234]

Very good videoes!

[@Manjot_singh2002]

7:28 import java.io.IOException; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; public class first { public static void main(String[] args) throws IOException { Comparator comp = new Comparator() { public int compare(String s, String t) { if (s.length() < t.length()) return 1; else return -1; // throw new UnsupportedOperationException("Unimplemented method 'compare'"); } }; List col=new ArrayList(); col.add("aaaaa"); col.add("aa"); col.add("aaaa"); col.add("a"); Collections.sort(col, comp); System.out.println(col); } }

[@stargaming3103]

Sir what is meaning of 1 and -1 . I didn't understand that

[@bharath3207]

you are the best

[@santoshchhetrithapa3573]

thank u sir very helpful . all clear now . Okay I have

[@hygef-v4]

thanks

[@prateekgoel7154]

Awesome video !!!

[@mrchaitu7]

Cannot make a static reference to the non-static field compare some times i am getting this error in quick fix i got add static static Comparator com = new Comparator() { then it solved

[@srikanthatthota2151]

what if i try to implement Comparator on Student class, Navin reddy please explain this scenario

[@sumantagorai5880]

1 for swap & -1 for no swap

[@xacademia9646]

you know the person teaching you about java is legit when he is bald hehe. subscribed :)

[@tsum3489]

My teacher in University who's teaching us java is also bald🤣 and he even looks so much like this youtuber!!

[@SrinivasKumar-v3c]

sir can u upload generics concept

[@SugamSangeetwdSavita]

Do we always need to use Array List for comparator or can it be used for array also??

[@PurushothamreddyRamigani-x6q]

I think no We can use any collection Correct me if I am wrong

[@AmitSingh-xc9qe]

Thankyou sir

[@GowthamE-l9r]

Nuvu king mava🤗

[@abhishekk3561]

I have a doubt .... how many times this swapping happens??

[@mazerati935]

thanks

[@sharabugnanesh3098]

7:20 import java.util.List; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; public class compa { public static void main(String[] args) { Comparator y = new Comparator() { public int compare(String i, String j) { if (i.length() > j.length()) return 1; else return -1; } }; List names = new ArrayList(); names.add("Gnani"); names.add("Gnan"); names.add("Chapathi"); names.add("Gnanesh"); names.add("navin mava"); Collections.sort(names, y); System.out.println(names); } }

[@codework2434]

Line no: 8 --> You have to specify Comparator on right side as well, its compulsory 3:03 . But I dono why it works without it.

[@sharabugnanesh3098]

​​@@codework2434 it's new update from official java it's unnecessary to mention on creating object of Comparator But in case of anonymous class we should! do you understand?

[@codework2434]

@@sharabugnanesh3098 So, in your code above you left to mention the type, right ?

[@sharabugnanesh3098]

@@codework2434 yes I need to mention at left

[@codework2434]

@@sharabugnanesh3098 Thanks about the "official java update"

[@-GANGUPALLIMAHAMMED]

Comparator is an interface so how object will created??

[@SharavananSrinivasan]

we are implementing the logic with lambda expression

[@ABHIJEETBHUJADE]

Can anyone help me waht is (a:) this label oprator why we use it

[@priyanshukhullar-tc7ss]

Thankyou Reddy Ji lots of love.

[@Shri577]

package basics; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; public class demo { public static void main(String[] args) { Comparator com = new Comparator() { public int compare(String i, String j) { if(i.length()

[@ESECYogeshS]

Sir the collection is not a class it's an Interface

[@Forty3Stories]

Collections is a class but Collection is an interface 😊

[@abhijeetkulkarni8246]

Sir please try to make videos with white screen

[@aminesaber467]

import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.Comparator; public class ChallengLQREA { public static void main(String[] args) { Comparator cmp = new Comparator() { public int compare(String o1, String o2) { if(o1.length() < o2.length()) return -1; else return 1 ; } }; ArrayList SortStrings = new ArrayList(); SortStrings.add("Amine"); SortStrings.add("Saberrr"); SortStrings.add("Aichaa"); SortStrings.add("Bahtiiii"); Collections.sort(SortStrings,cmp ); System.out.println(SortStrings); }

[@nazeebahmed1050]

I have a quetion, why by returning 1 , the swapping is happenning?It doesn't make sense to me,plz explain

[@audiomac]

Hello! Returning 1 means that a is greater than b. Returning -1 means b is greater than a. Returning 0 means a equals b. I hope this helps!

[@unemployedcse3514]

awesome ❤

[@dominicdumenil861]

import java.util.List; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; public class Student { public static void main(String[] args) { Comparator com = ( i, j) -> s1.length()>s2.length()? 1 : -1; List names = new ArrayList(); names.add("Nathan"); names.add("Dominic"); names.add("Nikita"); names.add("Sharon"); names.add("Jessica"); Collections.sort(names, com); System.out.println(names); } }

[@sayantanhalder1056]

Sorting string by length package Collection; import java.util.*; public class SortStringByLen { public static void main(String[] args) { ArrayList ob = new ArrayList(); ArrayList ob1 = new ArrayList(); Comparator c1 = new Comparator() { public int compare(String i ,String j){ if(i.length()>j.length()){ return 1; } else{ return -1; } } }; Scanner sc = new Scanner(System.in); System.out.println("Enter the names: "); String str; int len; for(int i=0;i

[@Vaishnav-zk2tf]

can any body tell me why return 1 and -1 is used .

[@actandrepeat]

Yes please..

[@abdulwadoodh5757]

How did you replace nums to studs?

[@kushagrasahni4597]

its just find and replace

[@sudeepbansal5234]

You are awesome 👏👏👏

[@ooogabooga5111]

You are explaining saying sort() works using bubblesort in the background, which need not be the case, don't give wrong info. In case of java it uses, duel pivot quick sort sort alogithm. Why you pass in comparator, you are only letting the sort know how to compare the values, not the whole sorting.

[@WolnośćUmysłu]

what is the IDE he is using?

[@zakirdeshmukh9916]

Vs code

[@sruthigudmella3322]

but IntelliJ IDEA works better

[@Raj-yy3dw]

import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; public class SortString { public static void main(String[] args){ // Comparator to sort strings by their length Comparator comp = new Comparator(){ public int compare(String o1, String o2){ return Integer.compare(o1.length(),o2.length()); } }; List words = new ArrayList(); words.add("banana"); words.add("apple"); words.add("kiwi"); words.add("strawberry"); words.add("pear"); words.add("orange"); Collections.sort(words, comp); System.out.println(words); } }

[@yashjoshi5709]

aaj mai alien banne vaala tha sir but aaj bhi merko aadhi cheeze samajh nahi aayi

[@shazirnazir3501]

public class SortNamesByLength { public static void main(String[] args) { List names = new ArrayList(); names.add("Rashid Khan"); names.add("Rohit Sharma"); names.add("Babar Azam"); names.add("David Warner"); names.sort(Comparator.comparingInt(String::length)); for (String name : names) { System.out.println(name); } } }

[@ROSHAN-HARI-BALAJE]

Ternary Operator ❌ Tatari Operator ✔

[@abhishekkumargupta9548]

opiest explaination

[@abukhandaker7558]

Too greedy with the ads